Genomic, Phenotypic and Environmental Correlates of Speciation in the Midwife Toads ( Alytes )
Year: 2025
Type: article
Abstract: Speciation, i.e., the formation of new species, implies that diverging populations evolve genetic, phenotypic or ecological factors that promote reproductive isolation (RI), but the relative contributions of these factors remain elusive. Here we test which of genomic, bioacoustic, morphological, and environmental differences best predicts RI across a continuum of divergence in the midwife toads (genus Alytes), a group of Western Mediterranean amphibians, using a total evidence approach. We found that, without strong geographic barriers to dispersal, the extent of introgression across hybrid zones between phylogeographic lineages, which should reflect the strength of RI, predominantly covaries with genomic divergence. Overall phenotypic differentiation becomes substantial only between well established, fully isolated species. These results suggest that speciation in midwife toads initially involve cryptic lineages, which probably evolve RI through intrinsic (genetic) hybrid incompatibilities. As they continue to diverge, these nascent species eventually differentiate externally, which potentially enforces pre-mating barriers and facilitates sympatry. This speciation scenario has practical implications for species delimitation, notably when using hybrid zones and divergence thresholds as proxies for reproductive isolation.
Source: Molecular Ecology
DOI: 10.1111/mec.17736
Authors: Johanna Ambu, Spartak N Litvinchuk, Carlos Caballero-Díaz, Alfredo Nicieza, Guillermo Velo-Antón, Helena Gonçalves, Fernando Martínez-Freiría, Helena Martínez-Gil, Juan Francisco Beltrán, David Donaire-Barroso, Axel Hernandez, Tomasz Suchan, Pierre-André Crochet, ĺñigo Martínez-Solano, Christophe Dufresnes
Institutions: Nanjing Forestry University, Russian Academy of Sciences, Institute of Cytology, Asociación Herpetológica Española, Universidad Autónoma de Madrid, Universidad de Oviedo, Instituto Mixto de Investigación en Biodiversidad, Universidade de Vigo, Universidade do Porto, Centro de Investigação em Biodiversidade e Recursos Genéticos, Institut de Recerca de la Biodiversitat de la Universitat de Barcelona, Universitat de Barcelona, Universidad de Sevilla, Université de Corse Pascal Paoli, Władysław Szafer Institute of Botany, Polish Academy of Sciences, Centre National de la Recherche Scientifique, École Pratique des Hautes Études, Centre d'Écologie Fonctionnelle et Évolutive, Institut de Recherche pour le Développement, Museo Nacional de Ciencias Naturales, Sorbonne Université, Institut de Systématique, Évolution, Biodiversité, Muséum national d'Histoire naturelle, Université des Antilles
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $5,150
OpenAlex ID: W4408845793